In the related art, as a reciprocating pump, a reciprocating pump in which a driving part including a crankshaft, a conrod, and the like is accommodated a crankcase and a cylinder portion is provided in a manifold connected to the crankcase is known (for example, refer to Japanese Unexamined Patent Publication No, 2010-53834). The reciprocating pump performs a pumping action of, by causing a reciprocating member to reciprocate in the cylinder portion as the crankshaft rotates, suctioning an operating liquid into a pump chamber formed on the tip end side in the cylinder portion, pressurizing the operating liquid, and discharging the operating liquid toward the outside.
In the reciprocating pump described above, in general, about half the inside of the crankcase is filled with an lubricating oil. Heat of the lubricating oil in the crankcase is dissipated toward the outside air from the surface of the crankcase and is absorbed by a manifold due to the operating liquid flowing through the manifold such that an equilibrium state is achieved. The lubricating oil in the crankcase obtains fluidity as being stirred by the rotation of the crankshaft and moves around sliding portions (metal contact portions) such as the crankshaft or the conrod such that the sliding portions are lubricated and cooled by the lubricating oil.